An embolization device is a surgical implant that is placed within an open site in the vasculature of the human body. The device is typically introduced via a catheter to the open site for endovascular therapy, e.g. control of internal bleeding, occlusion of blood supply to tumors, or relief of vessel wall pressure in the region of an aneurysm. For example, an implantable filament-based device is useful for ligament and tendon repair, vascular repair as an external support of the vascular graft to prevent kinking, and the treatment of aneurysm as an aneurysm sac space filling. See U.S. Pat. No. 5,263,984; Li et al. (1997) Trans. Soc Bomaterials 407; and Molyneux et al. (1995) J. Neurosurg. 83: 129.
There are a variety of materials that have been used to make such an embolization device. For example, a filament-based device is made of a heavy element such as a heavy metal itself (e.g., iron based stainless steel, nickel-titanium based nitinol, or platinum) or a combination of a heavy element and a polymeric material. It is visible by the X-ray analysis and, therefore, the position of the device can be precisely located and visualized once the device is deployed or implanted in vivo. However, there are many medical applications where a device made of a heavy element itself is not suitable, such as in ligament and tendon repair in which the biomechanical properties of metals are not compatible with the natural ligament and tendon.
This invention relates to an embolization device for occluding a vessel. This device includes a matrix made of a biocompatible and biopolymeric material and a radiopaque material, wherein the radiopaque material is interspersed in the biocompatible and biopolymeric material. The matrix can further include other agents, e.g., a growth factor, a clotting agent, or a surface active agent. The matrix of this invention can adopt a linear extended form or a folded relaxed form. It can be of mono-filament or multi-filament construction. Preferably, the biocompatible and biopolymeric material is biodegradable.
In one aspect, the embolization device of this invention includes a matrix that adopts a linear extended form or a folded relaxed form. One linear extended form the matrix may adopt is non-coiled, which can fold into a relaxed form, such as a spherical, a random, or a cylindrically coiled form. Another linear extended form the matrix may adopt is coiled, which can fold into a relaxed form as well, such as a spherical, a random, or a cylindrically coiled form. The coiled extended matrix defines a channel, in which a strand can be further disposed. The strand may be made of a biocompatible and biopolymeric material and adopt the linear extended form or the folded relaxed form as part of the matrix. It can be mono-filament or multi-filament construction. Preferably, the strand is made of a biocompatible and biopolymeric material that is biodegradable. Optionally, the strand is made of a biocompatible and biopolymeric material in which a radiopaque material is interspersed.
In another aspect, the embolization device of this invention can include a matrix and a sheath surrounding the matrix, wherein the sheath is made of a biocompatible and biopolymeric material. The sheath can further include other agents, e.g., a growth factor, a clotting agent, or a surface-active agent. As above described, the matrix can adopt a linear extended form, such as a non-coiled form, a coiled form, or a coil defining a channel in which a strand can be further disposed, and the sheath may adopt a linear extended form as well. The embolization device including the matrix and the sheath can adopt a folded relaxed form, such as a spherical, a random, or a cylindrically coiled form. Preferably, the sheath is made of a biocompatible and biopolymeric material that is biodegradable. Optionally, the sheath is made of a biocompatible and biopolymeric material in which a radiopaque material is interspersed.
In a further aspect, the embolization device of this invention can include a matrix, or a matrix and a sheath. The biocompatible and biopolymeric material used for this device can be a collagen (e.g., type I to type XIV collagens). As above described, the matrix can adopt a linear extended form, such as a non-coiled form, a coiled form, or a coil defining a channel in which a strand can be further disposed, as well as the sheath, if present, which is also in its linear extended form. The embolization device including the matrix and the sheath, if present, can adopt a folded relaxed form, such as a spherical, a random, or a cylindrically coiled form. Optionally, the sheath is made of collagen in which a radiopaque material is interspersed.
Also within the scope of this invention is a method of preparing an embolization device for occluding a vessel. The method includes steps of preparing a dispersion or a solution of a mixture of a biocompatible and biopolymeric material and a radiopaque material; reconstituting the mixture from the dispersion or the solution to form a filament; fabricating a matrix suitable for endovascular therapy, for example, with the filament or multiple filaments; crosslinking the matrix; and drying the matrix. Alternatively, the method includes steps of fabricating a matrix and a sheath suitable for endovascular therapy, for example, with the filament or multiple filaments; crosslinking the matrix and the sheath; and drying the matrix and the sheath. The matrix and sheath may be coated with a lubricious agent, e.g., a hyaluronic acid, to facilitate the delivery.